I have been toying of a model societies which essentially divides the population into three groups, those above the law, those below the law and a middle group.

Those above the law are simply those that can do actions with ounishment that would be punished if done by others.

Those below the law are those that easily gets punished even if they haven't done anything.

The middle group mostly has interactions were the law adjucicates disputes in between the middle group.

My general thrust is that these groups exists within at least all socities ruled by a states, but they can be smaller or larger. In the western post-war order the middle group was particularly large, encompassing most of the working class, the middle class and the lower upper class (owners of capital who doesn't wield power), but you also had an underclass that the police kept in line and an ruling segment of the upperclass that as long as they did their crimes through the system could and did get away with most things (as long as they didn't atttack fellow members of the ruling segment).

Those living under the law knows that the police are there to enact violence upon them and must be treated accordingly. You don't call the cops even if you have a conflict within your own segment because chances are that you will have violence enacted upon you.

Among the middle group there are isonomy in regards to the law,as long as conflicts are among themselves. (In conflicts between the middle group and those that are below the law the middle group wins as a rule, because the law is there to punish those below.) This creates an expectation that the law upholds justice etc and creates a willing target audience for copaganda and legal shows.

There is however not isonomy in conflicts between members of the middle group and members of the ruling elite, or the state itself. The state includes most prominently the police force, the actions of which are generally excused as long as it is in service of upholding the state through controlling the population (any sufficiently large demonstration is a threat against control no matter how peaveful) and some excuse can be invented (I have used the term "unreasonable doubt" to describe the contortions courts can twist themselves into to avoid the obvious conclusion that police broke the law).

I think a useful illustration of why these groups are not simply class based is the recent murder of Brian Thompson. Brian Thompson, as a ceo of a large company was a member in the ruling elite. His murder was therefore not just any murder, but a threat to the order of the US society. Somebody had to get punished before people start thinking that they could get away with killing a ceo and strating to figure out what the rulers are always acutly aware of: there are few of them and lots of us.

Luigi Mangione, the man who currently getting framed for the murder, is a member of the lower upper class, if you will. He comes from a real estate family, he has an ivy league education, but he is not a power player. I think the picked him on accident, they put up a massive reward and a McDonald's worker called it in in hopes of collecting (but got stiffed if I remember correctly) and then proceeded to first search his backpack without a warrant, then transporting it to the station, turning of body cameras for twelve minutes and then turing on the cameras and re-searching it and finding a murder weapon, a manifesto etc. But though picked on accident membership of the upper class has so far not protected him. Everything isn't said and done and he can afford really good lawyers who hopefully manages to punch out every excuse to sentence him, but the treatment so far (perp walk etc) is indicative of how a threat to the system is treated. Contrast with the kid gloves used on Trump or Clinton.

This is getting a bit rambling, but to conlude, I think   the amount of the population living in isonomy at least in relation to each other might be a useful measurement of equality, but in states there are always above and below too. And of course we are all moving in the wrong direction.